1. Field of the Invention
The present invention relates to an arc discharge method, an arc discharge apparatus, and a fused silica crucible manufacturing apparatus, and more particularly, to a technique suitable for preventing electrode oscillation during arc discharge when vitreous silica powder is heated and melted for vitrification.
Priority is claimed on Japanese Patent Application No. 2008-242874, filed on Sep. 22, 2008, the content of which is incorporated herein by reference.
2. Description of the Related Art
A fused silica crucible used for pulling single-crystal silicon is generally manufactured by an arc melting method. This method is a method of manufacturing a fused silica crucible by accumulating vitreous silica powder on an inner surface of a mold made of carbon, providing carbon electrodes above the vitreous silica-deposited layer, and heating the vitreous silica-deposited layer by the arc discharge for vitrification.
Japanese Patent No. 03647688 discloses a technique related to arc melting in a manufacturing process of a fused silica crucible by arc melting, and JP-A-2002-68841 discloses a technique related to electrodes used for arc discharge.
In addition, recently, due to demand for higher efficiency of device operation, the diameter of a manufactured wafer has increased to over 300 mm, and for this, there is a requirement for a fused silica crucible capable of pulling single crystals with a large diameter. In addition, due to demand for a reduction in size of a device or the like, there is a strong demand for improvements in crucible properties such as an internal state of a fused silica crucible, which may directly affect the properties of single crystals under pulling.